On Thu, 2007-05-17 at 20:30 +0000, Matthieu CASTET wrote:
> On Thu, 17 May 2007 10:29:31 -0700, Andrew Morton wrote:
>
> > On Thu, 17 May 2007 18:09:50 +0300 Artem Bityutskiy
> > <[email protected]> wrote:
> >
> > umm.. I'd say what you've done in there is an improvement to the
> > exiting stuff: getting gcc to check it is better than having to use
> > sparse.
> >
> > I'd have expected gcc to generate poorer code with your approach but I'm
> > showing zero text size changes from Christoph's patch (gcc-4.1 and
> > gcc-3.4.5).
> >
> >
> On which arch did you try ?
> X86 where unaligned access are ok ?
>
> On arch that don't support aligned access, packed struct access will be
> done byte per byte (but it could be the expected behavior if there
> unaligned access).
When I tested this on ARM, the output for je32_to_cpu et al was fine.
For _other_ structures where I'd used __attribute__((packed)) to be
safe, gcc would emit code to handle unaligned loads. But not in the
simple case where the struct has only one member.
Are you suggesting that this has changed since I did my testing?
--
dwmw2
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